Analysis of Acid-Base Complexation Reaction Patterns of Salvianolic Acid B and Matrine During Compatibility of Salviae Miltiorrhizae Radix et Rhizoma and Sophorae Flavescentis Radix Based on a Quantitative Model of Component States

• • Ultrafiltration-nanofiltration coupling resolved matrine ionic and molecular states with power-function correlation coefficients >0.97, enabling quantitative state analysis in complex TCM solutions where empirical structural control previously failed. • • In SFR extract alone, matrine existed as 36.90% ionic, 61.98% associated, and only 1.12–1.91% molecular states, establishing that molecular matrine is negligible and that associated forms dominate baseline extraction behavior. • • Increasing SMRR compatibility ratio shifted matrine ionic fraction from 66.73% down to 45.83% while complex state rose from 31.87% to 52.90%, demonstrating that acid-base complexation is ratio-dependent and directly alters mass transfer during manufacturing. • • The model is applicable to acid-base dominated systems such as alkaloid-phenolic acid and alkaloid-tannin pairs, but has limitations for multi-component systems with superimposed interactions, requiring complex/associated species separation coupled with NMR or small-angle X-ray scattering for structural resolution.